Insulation in an electron tube



Oct. 28,1947. B. R. coRsoN INSULATION IN AN ELECTRON TUBE Filed Feb. 2, 1944 VENTOR 0/6 011/ ATTORNEYS Ba y a /d 1?.

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INSULATION IN AN ELECTRON TUBE Bayard R. Corson, Newburyport, Mass, assignor to Hytron Corporation, ac'orporation of Massachusetts Application February 2, 1944, Serial No. 520,737 I This application relates to an electron tube, more particularly to insulation in the tube which is used asan electrode support.

In certain electron tubes, one example being those used as a voltage regulator, some sort of insulation, usually mica, is mounted on the anode and extends to the cathode support. The Mish metal which is sputtered in the tube is usually mounted on the anode and the sputtered material frequently coats the surface of the insulating material so that its insulating properties are lessened or destroyed. This film is sometimes broken by coating the insulating material with something or other that will roughen the surface while in other cases a slot is provided in the insulating material, The coating has the disadvantage of introducing an impurity into the tube and is not always effective if the film of sputtered material is heavy. The slot has the disadvantage of weakening the insulating material and also when the film is heavy it may be impossible to introduce a slot which will be capable of breaking the leakage Without cutting the mica in half. Particular difiiculty-has been had in a voltage regulator tube.

One of the objects of this invention is to maintain the good insulating properties of the insulating material by completely breaking anyinsulating film which may be deposited thereon.

Another object of this invention is to provide a closed metal free path about one of the electrodes on the insulating material which cannot be reached by the sputtering of Mish metal within the tube.

A further object of this invention is to provide a break in any deposited film without roughening the surface of the insulator and without slotting the insulator, thereby avoiding any contaminating material and maintaining the strength of the insulator.

With these and other objects in view, the invention consists of certain novel features of construction, as will be more fully described and particularly pointed out in the appended claims.

In the accompanying drawings:

' Fig. 1 is a sectional view through the tube with the insulation therein comprising my invention;

Fig. 2 is a fragmental sectional view on an enlarged scale;

Fig. 3 is a section on line 3-3 of Fig. 2; and

Fig. 4 is a section on line 44 of Fig. 2.

In proceeding with this invention I locate at a point between the insulating material and the metal to be sputtered, a shield which is spaced :from the surface of the insulating material so as 4 Claims. (01. 250 -27 5) to provide a gap at the edge of the shield and so as to protect and'prevent deposit of the exploded material on the surface of the insulating material. A convenient means of carrying out this thought is to use some spacer for the shield and attach it permanently to the insulating material, the spacer being of smaller diameter so as to leave the edge of the shield free.

With reference to the drawings Ii! designates an envelope of glass having a base H with contacts l3 and I4. Stem press l5 mounts a suitable anode !6 which has a connecting lead H with the contact I3. The Mish metal to be sputtered is designated 18 and is mounted upon the anode it at a point spaced from the upper end thereof.

The stem press also has extending therefrom support wires 20 connected by leads 2! to the contact I4 and which support wires mount the cathode 22 which is of cylindrical shape with its axis coaxial with the anode 16. The two insulator units 23 and 24 serve as means for spacing the cathode relative to the anode.

Each of these insulating units consists of an insulating disc 25, such for example as mica, which is provided with suitable means 26 for attaching it to the support wires 29. A shield 2i, which may be of the same material (mica as illustrated) as the disc 25, is located below the disc 25 and in space relation thereto. A suitable arrangement to provide for such a spacing is to provide an element 28, of a size smaller than the disc 2'! so as to leave a space 29 between the discs 25 and 21. These three pieces 25, 21, and 28 may be eyeleted together as at 3B which provides a suitable mounting for securing the insulating unit 23 or 24 upon the anode 16.

In this arrangement when the Mish metal 18 is exploded it will travel in the paths of the lines 3| upwardly and downwardly as shown in Fig. 2 and will strike the shield 21 and also the insulating disc 25 at a point which will be outwardly from the shield 21. However, the difference in area of the shield disc 21 and the small spacer disc 28 will provide a closed clear path on the disc 25 which will not be contacted by the vaporized or sputtered metal. Consequently, this unbroken closed path 32 which exists about the anode and between the anode and the cathode will prevent the conduction of any electrical current from one electrode to the other and thus provide a good insulation between the two.

By eyeleting the three pieces together, 25, 21, and 28, a convenient assembly is provided which may be easily handled and mounted in position in the manufacture of the tube.

3 I claim: 1. A tube comprising an anode, a cathode, an insulating spacer therebetween, a source of sputtered metal on one side of said spacer and a shield parallel to and spaced from said insulating spacer and supported thereby and between it and said metal of a shape to provide a closed metal free path between said anode and cathode from the projection of said metal from its source.

2. A tube comprising an anode, a cathode, 'ari insulating spacer therebetween comprising a disk, a source of sputtered metal on one side of said disk, a smaller second disk on said side and a third disk of a size smaller than the second disk between said disks to provide a space between said first and second disks.

3. A tube comprising an anode, a cathode, an

insulating spacer therebetween comprising a disk,

a source of sputtered metal on one side of said disk, a smaller second disk on said side and a third disk of a size smaller than the second disk between said disks to provide a space between said first and second disks and means to secure said disks together.

4 4. A tube comprising a cylindrical cathode, an anode carrying a getter, a spacing element extending between said anode and cathode comprising insulating material, a shield between said getter and spacing element, means spacing said shield from said spacing element and of a size smaller than said shield whereby to provide a closed metal free path between said anode and cathode from the projection of said getter.

BAYARD R. CORSON.

QEEERENCES CITED The following references are of record in the file'of this patent:

U grrgp STATES PATENTS 

